During operation of a gas turbine engine, pressurized air from a compressor flows into a head end volume defined within the combustor. The pressurized air flows from the head end volume into an inlet to a corresponding premix passage of a respective fuel nozzle assembly. Fuel is injected into the flow of pressurized air within the premix passage where it mixes with the pressurized air so as to provide a fuel and air mixture to a combustion zone or chamber defined downstream from the fuel nozzle. The fuel and air mixture is burned in the combustion chamber to produce hot combustion gases.
The fuel may be supplied to the fuel nozzle(s) via a conduit or tube which extends downstream from a flange. The flange may be connected an endcover or outer casing of the combustor. In certain configurations, a first or upstream end of the tube is connected to a stem of the flange via a flexible coupling and a second end of the tube is coupled to a body of the fuel nozzle assembly. The flange and the tube define a fuel passage between a fuel supply and the fuel plenum. The flexible coupling allows for differential thermal growth between the flange and the fuel nozzle body. Joints formed between the flexible coupling and the tube may be compromised over time.